tonight and to what could a pivotal day in the trial of neighborhood watchman george zimmerman, accused of murdering trafeoon martin. Martin's mother taking the stand, saying the voice screaming for help was her son. The prosecution resting its case and the defense demanding an acquittal. What did the judge do. Matt gutman is in sanford, florida at the zimmerman trial again tonight. It was the emotional crescendo of two weeks of testimony. So you think he's will yelling help? Yes. Two mothers on the stand, each claiming to hear their own son in these screams. The grieving mother of trayvon martin. Who do you recognize that to be? Trayvon benjamin martin. And george zimmerman's mother? Who's voice that was? My son george. It symbolized two weeks of proceedings, the prosecution beginning its case with a head snapping opening statement. punks. These always get away. Reporter: Prosecutors hammering at zimmerman's credibility, catching him in inconsistencies. There were two people involved here, one of them's dead. One of them's a liar. Reporter: But the prosecution's case undercut by several of its own witnesses whose testimony appeared to help the defense. The eyewitness who saw martin on top of zimmerman that night. He was the one who was reining blows down on the person on the bottom, george zimmerman? That's what it looked like. Reporter: The lead investigator called by the prosecution saying he believed zimmerman's inconsistencies were minimal. Is there anything else in this case where you got the insight he might be a path lonl cal liar? No. Reporter: After the prosecution wrapped, the defense said the case is so weak, they demanded the judge throw it out. What is before the court is an enormous amount of information that my client acted in self-defense. Reporter: They could wrap their case by the midil of next week. The big question, will zimmerman take the stand? I spoke to his attorney mark o'mara, he said it's not likely.

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